Mass Spectrometry of Organocobalt Derivatives

Abstract

Being one of the most powerful and versatile analytical techniques, mass spectrometry has greatly contributed to the analysis of organocobalt derivatives. After a short discussion of the ionization methods most relevant to the investigation of these species, this chapter reviews the application of mass spectrometry to the analysis of the title compounds. First, these applications include the characterization of preformed organocobalt derivatives, such as cobalt complexes with σ‐bound organyl groups, cobalt complexes with organic π‐donor ligands, and carbonyl‐containing cobalt clusters. In these cases, mass spectrometry is typically used as a routine technique, together with additional analytical methods. Second, mass spectrometry, particularly its electrospray‐ionization (ESI) variant, can also be employed for the detection and identification of in situ formed organocobalt derivatives. While ESI mass spectrometry is limited to the analysis of charged species, this method has succeeded in the observation of several quasi‐neutral organocobalt intermediates bearing a charged tag. From the time profiles of the ESI signal intensities of these intermediates, valuable information on the reaction kinectics could also be obtained. Finally, mass spectrometry has been extensively applied to the gas‐phase preparation and analysis of organocobalt derivatives. In the highly diluted gas phase, even very reactive organocobalt ions can be generated and further examined. Tandem‐spectrometry permits the mass selection of these ions and thereby greatly facilitates their analysis. Thus, gas‐phase experiments probing the uni‐ and bimolecular reactivity of organocobalt ions have afforded seminal thermochemical and mechanistic information. Coupling tandem mass spectrometry with gas‐phase spectroscopy has moreover furnished insight into the structures of organocobalt ions.